490 THE SOOTY MOULD OF CITRUS TREES, 



Florida Aschersonia tahilensis, Mont., has been found attacking 

 and destroying the larvje and pupse of the " Mealy Wing " 

 {Aleyrodfs cilri, R. and H. ), and bids fair to be of great use in 

 combating the pest. This latter fungus has also been met with 

 in Queensland on the foliage of a large climber, but no mention 

 i.s made of its connection with scale or other insects. 



Effect on trees — This fungus does not produce any marked 

 injury to the tree at first, as when the " sooty mould " is removed 

 from a leaf the surface beneath is often as green and glossy as a 

 healthy one. The injury is rather of a mechanical nature, and, 

 combined with the scale insects sucking the juices of the plant, 

 there is often considerable damage done. The fungus will interfere 

 with the process of assimilation, by preventing the access of light 

 and the escape of watery vapour and other gases. Indirectly 

 this will hinder the growth of the tree and affect the production 

 of bloom and of fruit. The leaves are less able to stand the 

 efiects of drought or other unfavourable conditions, and if the 

 young fruit is attacked by it its development is hindered and it 

 generally remains insipid. 



Treatment. — It will be evident from the preceding remarks 

 that the only sensible treatment will be to get rid of the lion's 

 provider; and whatever insect provides the pabulum for the fungus 

 to flourish on, should be dealt with. Mr. French, the Government 

 Entomologist of Victoria, informs me that the principal scale 

 insects attacking the Citrus leaves infested b}^ " sooty mould " are 

 the red scale of the orange (Aspidiotus coccineus, Gennad.) and the 

 black scale ( Lecanium olece, Bernard), and for these the treatment 

 he recommends is the kerosene emulsion or resin wash. In a 

 pamphlet issued this year by the U.S. Department of Agriculture 

 on " The principal diseases of Citrous fruits in Florida," by W. 

 T. Swingle and H. J. Webber, spraying with resin wash or 

 fumigation with hydrocyanic acid is said to be very effective. 



In the course of this investigation I found a fungus-parasite on 

 the scale insects on leaves with "sooty mould" from N.S.W. 

 This fungus, already known in Europe and hitherto only met 

 with in Queensland, might become a useful ally in the treatment 



